S&P said it not longer saw UDC's business an integral part of the ANZ group strategy.
"In addition, we also no longer consider that UDC's business is integrated with the ANZ group to such an extent that it would be improbable to sever the subsidiary from the group," it said.
"In our assessment, we have also taken into account a recent shift in the strategic focus of banking conglomerates in Australia and New Zealand - including the ANZ group - to rationalize their business mix," it said.
S&P noted that ANZ group has had a long-standing history of providing funding support to UDC in the form of a committed credit facility for $800 million.
A high number of UDC customers share other banking relationships with ANZ in New Zealand.
"And as such, we believe incentives exist for the broader group to support the subsidiary during this transition," it said.
UDC Finance has been involved in providing finance for the transport, forestry, agriculture and manufacturing sectors for several decades.
In 1980 ANZ bought 100 per cent of UDC, resulting in UDC Finance becoming a wholly owned subsidiary of ANZ Bank New Zealand.